1. Field of the Invention.
This invention relates to soldering irons and, more particularly, to improved soldering irons providing an air current directed toward the vicinity of the work.
2. Description of the Prior Art.
Despite current improvements in technology which permit the automated production of electronic equipment, printed circuit boards and the like, there are still fields of application where human operators are required to use electrically heated soldering irons on production lines for electrical apparatus. There are two principal problems which relate to the use of soldering irons in this fashion.
One problem relates to the noxious fumes which are developed from the vaporizing of solder flux as the flux is used in conjunction with the soldering process. There are also fumes from the overheating of wire lead insulation to contend with. Flux is commonly used during the soldering step to control the oxidation of the parts being joined so that the solder will develop a better joint. This flux, usually in resin or paste form and sometimes constituting the core of hollow core soldering wire, is somewhat caustic, particularly when heated, and the fumes are extremely noxious, even to the point of being hazardous for human operators to breathe. Yet the flux is a necessary ingredient in the forming of a good solder connection.
Another problem relates to the heat generated in the soldering process. The soldering iron is usually maintained at an elevated temperature for hours at a time, ready for use by the operator in completing the soldered connections. It is desirable to make the tip of the soldering iron, including the heating element extending from the handle to the tip, fairly short, in order to reduce the cantilevered weight which is supported from the handle and thus reduce the fatigue experienced by the operator from continually manipulating the soldering iron for long periods of time. However, having a short tip and heating element of the soldering iron merely exacerbates the problem of heat from the tip reaching the handle during long periods of operation. Efforts have been made to reduce the heat which reaches the handle from the tip by providing heat deflectors or radiators, such as fins encircling the heating element, and similar arrangements. These tend to defeat their intended purpose, however, since they add weight to the cantilevered portion of the soldering iron, even though they may permit a shorter cantilevered portion in a soldering iron designed for continuous operation.
The prior art contains a number of examples of attempts to solve one or another of the problems associated with the use of an electrically heated soldering iron. U.S. Pat. No. 3,121,781 of Schoenwald discloses an electrically heated soldering iron having a specially constructed handle which is designed to accomplish convection cooling. A plurality of vents are strategically located in conjunction with hollow spaces within the handle so that air is vented to flow into the interior of the handle and outwardly through some of these vents under the influence of convection.
U.S. Pat. No. 3,141,088 of Johnson discloses a handle configuration having provision for air spaces between the finger grip portion of the handle and the heating element of the soldering iron. The special structural configuration of U.S. Pat. No. 3,134,884 of Bean, Jr. includes a hollow handle portion, particular metal parts of stainless steel between the handle and the heating element for limiting the transfer of heat towards the handle and of aluminum within the handle itself for spreading and distributing the heat within the handle away from the finger grip portion, as well as a pair of disk radiators situated between the heating element and the handle to protect the user's fingers from radiated heat emanating from the heating element.
Cranor et al in U.S. Pat. No. 4,358,662 disclose an arrangement for exhausting fumes from the vicinity of a soldering iron tip. This is in the form of a fume exhausting attachment which may be mounted coaxially of the heating element barrel, adjacent the tip, with provision for connection to a vacuum source so that objectionable fumes, gases, smoke and other airborne contaminants may be withdrawn from the soldering site.
Other patents of but slight interest to the concepts of the present invention include U.S. Pat Nos. 3,980,218 and 4,419,566 of Fortune relating respectively to a vacuum desoldering system and a hot air soldering and resoldering system, and U.S. Pat. No. 3,080,470 of Davis which discloses a portable-gun-type spot welder with provision for directing cooling air at the welder tip to protect it against overheating.
Insofar as the known prior art is understood, none of these patents discloses any arrangement operating in the manner of the present invention, nor does any patent disclose any arrangement for dealing simultaneously with the two principal problems outlined above in the use of manually operated soldering irons.